New Insects Released To Control Hieracium
As a further step in the Hieracium Control Trust programme, two further insects are to be released into the field to control three hieracium species, a herbaceous weed invading much of the hill and high country of New Zealand.
The Hieracium Control Trust and Landcare Research have released into the field near Tekapo, a gall midge, Macrolabis pilosellae, whose larvae feed within the galled leaves of three species of hieracium. And a hover fly, Cheilosia urbana, whose larvae feed on the roots of four hieracium species is due to be released in North Canterbury next week. Chairman of the Trust, Mr John Aspinall said that 'the trust is delighted to be able to make these releases following approval given by the Environmental Risk Management Authority last June to import and release a further three insect species.'
This follows on the earlier approval of a gall wasp, which, has now been released at 52 sites including the central North Island, with establishment already confirmed at 15 sites. A plume moth has also been released into the Mackenzie Basin. And a rust and a powdery mildew are widely dispersed.
Landcare Research scientist, Mr Lindsay Smith, said that 'the insects have been closely scrutinised to select the most promising species and ensure that they do not attack other plant species. This was a necessary requirement before the application was approved by the Environmental Risk Management Authority.'
A fifth insect species has been approved and will be released next summer.
Mr Aspinall said that 'this represents the culmination of a $1.4m programme targeted at implementing a biological control programme for hieracium. We sincerely thank all those who have made the programme possible by contributing funding, which has come from a wide range of agricultural, community and Government interests. The Trust's main focus is now the importation, rearing and release of the 5 approved insect species, and monitoring of results'.
Mr Aspinall concluded by expressing the Trust's concern that 'only one insect attacks hieracium lepidulum, a major threat to conservation areas. However, if further work is to be done to combat this species, conservation interests will have to take a much greater role.'